我国近代第一部有声电影是[ ]
A.《定军山》
B.《歌女红牡丹》
C.《渔光曲》
D.《一江春水向东流》
答案:B
The lawyer required the ____ of evidence so that he could defend the accused.
A.judgment
B.contribution
C.subscription
D.presentation
简述什么是观察学习?